THE EXTENT OF THE SIDEREAL HEAVENS. 359 



off. Among the myriads of faint stars which we see from 

 our observatories there may be many, indeed there must 

 be many, which are fully a thousand times as distant as 

 the bright stars which twinkle in our comparative neigh- 

 bourhood. We thus obtain some conception of the stupen- 

 dous distance at which the outskirts of the universe are 

 situated. There are different ways of illustrating this 

 point, but I think the simplest, as well as the most striking, 

 is that which is founded on the velocity of light. It is a 

 remarkable fact that the beautiful star known as Yega has 

 a distance from us so tremendous that its light must have 

 taken somewhere about eighteen years to travel hither 

 from thence. Notwithstanding that the light dashes 

 along with such inconceivable speed that it will cover 

 185,000 miles in every second, notwithstanding that a 

 journey at this pace will complete the entire circuit of this 

 globe seven or eight times between two successive ticks of 

 a clock, the light will, nevertheless, take eighteen years to 

 reach our eye from the time it leaves Vega. We do not, 

 therefore, see the star as it is at present ; we see it as it 

 was eighteen years ago. For the light which this evening 

 enters our eyes has been all that time on its journey. In- 

 deed, if Yega were actually to be blotted out from exist- 

 ence it would still continue to shine out as vividly as ever 

 for eighteen years before all the light on its way had 

 reached us. 



We have been led to the belief that among the more 

 distant stars in the universe there must be many which 

 are fully a thousand times as far from us as is Yega, hence 

 we arrive at the startling conception that the light they 

 emit has been on its journey for 18,000 years before it 



